Heretofore, there is known a control device that is provided with a relay capable of switching between connection and disconnection between a power supply circuit and an electrical load, a plug capable of disconnecting the power supply circuit (safety plug, service plug), and a contact point capable of switching between connection and release according to attachment/detachment of the plug, and that controls opening/closing of the relay according to opening/closing of the contact point (for example, refer to Patent Documents 1 and 2).